Is there anyway I can convince my mom's to change her mind?

I asked a question similar to this one a while ago. It was about the
midnight premiere of Harry Potter, and how she wouldn't let me go.
Well, after her thinking for about two weeks she told me that I wasn't
allowed because the doesn't want to have to pick me up at 3 in the
morning, and she doesn't want me out at 3 in the morning. We just went
to pre-buy tickets for the next showing (i think it's around 11am.)
And when I asked the lady who works there about the midnight premiere
there are only 20 seats left and it is going to one of their craziest
nights. On the way home from buying the tickets my sister and I were
trying so hard to be thankful, but we both just looked at each other
and started crying. We tried to explain to our mom how much this means
to us but she wouldn't listen. My sister and mom started fighting and
the next thing I know my mom is calling the movie stupid which made my
sister and I more upset. I love my mom, but I feel she has NO CLUE how
much this means to my sister and I. This is honestly our childhood,
and means the world to us. What can I do? I am so upset and i'm trying
to be happy but nothings working? There are only 20 seats left and I
SO BADLY WANT TO GO.
I just need advice...like now